While rooftop farming has cropped up in a number of cities across the country, it has yet to take root in Boston. But this will soon change when founders Courtney Hennessey and John Stoddard launch operations of their new rooftop farm, aptly called Higher Ground Farm, located atop the Boston Design Center this Spring. According to CoLab Radio at MIT, the duo will start planting on a 40,000-square-feet segment of the expansive 55,000-square-feet roof within the next few months and be ready to sell the fresh produce by summer.